Pulley



United i States Patent "ice 2,944,434 PULLEY y f .Carl W: Mott, VLake Ozark, Mo., assignor to Mott Corporation, Brookfield, Ill., a corporation of Illinois Filed Apr. s, 1957, ser. N0. 651,274 1z Claims. (ci. 'I4- 230.10

flanges and unique means for retaining such elements in assembly. Y

Pulleys of this general character are useful upon the power output shaft of a power source'asan internal combustion engine for driving and propelling lawn mowers. When the engine iand pulley are latrest the inertia weights are retracted 'causing axialseparation of thepulley flanges and release of the belt so no load is transmitted through the belt while cranking they engine. When the engine attains operating speed the centrifugal force of the weights causesv the pulley flanges to grip the belt with suicient force to transmitV the desired amount of power through the belt. Should the load eventually exceed the engine power, causing the engine to decelerate, the centrifugal force will` diminish and Athe consequential diminished gripping of the pulley flanges on the beltwill allowrit to slipwith respect to the Vpulley to lighten the engine load and prevent stalling. Thev use of a centrifugal pulleywith opposed conical beltengaging surfaces on the flanges with a V-type belt enables the pulley to expand kthe belt as it is drivingly gripped, wherefore such pulleyalso serves as an automatic belt tightener.

An important object of this invention is the provision of a pulley, constructed principally of two complemental belt-driving elements eachhaving a hub, a web and a ilange-carrying rim, assembled with the hubs and rims telescopic, while the webs'are axially spaced to provide an annular protective enclosure for the inertia-weights. It is also contemplated that at least one of the rims or hubs shall .be piloted on the rim or hub with which it is in telescopic relation. y v

Another object of this invention is the provision of a novel arrangement lof assembly pins which prevent axial disassembly of the belt-driving elements and which also receive driving force from the centrifugal weights for forcing the flanges into gripping relation with ythe belt. These and other desirable objects inherent in and encompassed by the invention are elucidated in the ensuing specification, the appended claims and the annexed,V

- drawings, wherein:

Fig. 1 is an axial seetional'vicw of a preferred embodiment of the invention, illustrating the pulley flanges k axially spread to release the belt.

',rnent, together with the inerta'weights mounted thereon.v

`the weights that straddle the bosses 35.

side diameter ofthe springs so the springs insert firmly Patented July 12, 1960 Vjects radially therefrom, and at the outer edge ofthe face receiving andtelescopically piloted upon a cylindrical surface `24 of the hub 13. A web 25 of the beltdriving member 12 extends radially outwardly from the hub v2-2' where it supports an annular rim 26 on which there is an annular ange 27 having an annular conical belt-engaging surface 28 in opposed spaced relation with respect to theconical belt-engaging surface 21 of the belt-driving element 11.V Rim 26 has a cylindrical inner periphery 29 piloted upon a cylindrical outer periphery 31 of the rim -18 for axial telescopic movement.

A belt B is looped'lSO" about the pulley by being dis- .posed within the groove G'formed between the flanges 1 9 and 27. lIn Fig. l lthe belt-driving element 12 is shown axially retracted leftward with respect to the element 11 for loosening the belt which has a'keystone cross-section and thereby establishes a condition of no-drive between the pulley and the belt. In Fig. 2 the belt-driving element 12 is axially advanced rightward with respect to the element 11 whereby the belt engaging surfaces 21 and 28 are forced into gripping relation with the converging sides 32 and 33 of the belt B. This gripping action of the belt-engaging surfaces 21 and 28 upon the belt expands it radially of the pulley to tighten the belt between this pulley and a complemental pulley (not shown) upon which the other end of the belt is conventionally looped.

The axially spaced-apart webs 17 and 25 of the beltdriving elements 11 and 12 together with the hubs .13 and 22 and the rims 18 and 26 enclose an annular 1nertia-weight-receiving chamber 34.

'In Figs. 1, 2 and 4 the hub 13 can be seen `to have diametrically opposite bosses 35 upon which inertia Weights 36` are respectively mounted by means of pivot pins 37Y which are mounted in bores 38 in the` bosses 35 and 'extending into'bearing bores 39 in furcations 41 of Weights 36 are assembled vwith the bosses 35 -by means of the pins 37 before the moveable belt-driving element 12 is assembled with the element 11.

In Fig. 4 diametrically opposite spring receiving bosses 42 and 43 are visible as well as spring receiving seats 44 and 45 in these bosses.- Web 25V has diametrically opposite notches 42a arid43a for respectively receiving theV bosses 42 and 43 when the parts 11 and 12 are axially assembled. In Figs. 3 and 4 it can be seen the boss 42 exceeds the boss 43 in diameter land that the span of the notch42a exceeds the span .of

the notch 434.50 the elementsv 11 and 12 can be assembled only with the bossesv 42 'and 43 respectively in the notches 42a and 43a.` Helical compression springsV 46 are disposed in'the recesses 4421, and 45a beforeraxiallyr j v assembling the-pulley elements 11 and 12, it'being ascer? tainablein Fig. 3 the diameters'of the recesses or spring seats 44aand 45aare substantially the sameas the out- Belt-driving element .12in its Y 3 in these seats. lOn the other hand the recesses or seats 44 and 45 are slightly oversized in diameter with respect to the springs Aso the right ends of these springs as observed in 'Figs l and'Z can be morerrea'dily piloted into the recesses44 and 45 'attendant'to assembly of the pulley elements 11 and I2. l

xial assembly of the pulley elements '11 and "12 is accomplished attendant to inserting the free `or' 'right ends ofthe springsas observed inFigs. l 'and 2'into'th`e spring seats 44 and 45 ofthe yelement '11fan`d 'the springsrare compressed betweenthe Qelementsas the bosses l2 and '43 areprojected into thenotc'hes 42a and 43aand asrthe hub pilotingfsurfaces 323 :and the.rim'piloting4 surfaces 29 and 31 are placed in axial t'e'lescopicrelation -After such telescopic associations lof `the lpulley elements T.11 and .512, assembly retaining pins 47 are 'inserted respectively vthrough upper ,bores 48 extending chordally .through the rim 26 and likewise .through @coaxial lbores 49 at the lowercpart ,of theelement 12 as lsliown in the Ndrawingsl l These retaining pins-4.7 aire dispsed between Athe centrifugal weights 36andtthelweb '17.ofthepulley element 11. These pins '47* are abuttable bythecentrifugal weights .36 irrespective of Ywhether cthepulley elements Il .and ,-12 are axially expanded as illustrated in 'Fig. l or axially contracted asillustrated in 'Fig.;2 topgprevent accid'ental disassembly-of the elements 11 and 12. lItwill be noted, from 'an inspection of Figs. I and 2, that ,the right- =hand faces of the weights 36 slant outwardly and tothe .left, as viewed in these gures. These vfaces thus constitute plane camA surfaces obliquetoa radius, which bear ,axially againstthe pins 47 and thus move elements 11 zand 12 towardeach otherras-the-weights move radially.V

During rotation of thepulley :theweights `36 revolve .aboutpthe principalcommonaxisof 'the-shaft -15 and the hubs 13 and 22.to develop centrifugal vforce `which isof aamagnitudeconstituting Va` direct function ofpulley speed.

*rimsther'eof being axially'telescopically disposed and at :The pivot-pins ,37 and y"thevrrassernblyretaininggpins 47 V serve las weight;reaction elements to which V.this centrif- :nigal-.force' ofthe weights is applied for .moving the beltdriving :elements faxiall-y toward one another in .opposi- =tion `to the 'yieldably urging means ;i11^theform of the vsprings :46 for pressing the `belt-engaging fsurfaces YZLand 'v2-8 Ain ygripping relation .with `the sides of Athe belt .with a force constituting ia:directfunction1of the pulley rotaftional speed.

Having Idescribed a single preferred embodiment of the -inventionwith the-.view fof clearly and `concisely illustratingaV the same, Lclaim:

1. A belt-driving pulley-:comprising eomplemental beltdriving 'elements .each 1 including a hub, :a web -extending radially outward-fromthehub, an'axially extending Epilot Trim. on :a` radially :outward portion of the iweb, 1and a iiange .projecting radially outward tour the orimfto idispose :a conical belt-engaging surface ofsuch flange coaxially .with the hub, the yhubs tof such elements and -the rims :thereof beingaxially ltelescopically disposed-and'at least aonefof such hubs andrimsbeingipilotedOnfthe one telescopically disposed therewith, the ,Webs of suchelements heing Aspacedapart axially of the :hubsiand `rims wherefforeithe hubs, webs and rims .form .an annular weightf'receiving chamber, Ameans :yieldably :urging the 'elements axially apartftolincreasethezafxial spacingbetweenthebeltfengagng surfaces, *weight reaction elementstini said chamber :fand .respectively on the belt-driving elements,` centrif- :ugal .weight means dispose.d;in said: ch-am`ber;fora1evolving `about the axis :of the\hubs #toadevelop centrifugal force rattendant 'to rotation ofthe tbelt-riving .felernents, :and ithe .centrifugal 'weight :means beinglioperable :to apply .fcomponentsf'of .the `centrifugal force to fthe weighttreac- 4:tion .elements `-for -`moving the abelt-driving elements frelaztively iaxially toward one another in ioppositien =to the f yieldably urging means :and pressing thejbelt-.enga'ging :surfaces :in gripping :relation 'with :a belt :therebetween jwith a fforcezconstitutinga direct functionfofthe pulley rotational speed.

2. A belt-driving pulley comprising complemental beltdriving elements each including a hub, a web extending radially outward from the hub, an axially extending pilot rim on a radially outward portion of the web, and a ange projecting radially outward from the rim to dispose a conical belt-engaging surface of such ange coaxially with the hub, thehubs vof such elements and the rims thereof being axially telescopically disposed and at least one of such hubs and rims being piloted on the one telescopically disposed therewith, -the lwebsfof such-elements being spaced rapartaxial'ly f'the lhubs andrims wherefore the zhubs, webs and rims form fan annular weight-receiving chamber, means yieldably urging the elements axially apart Y'to increasethe axial spacing between the belt-engaging surfaces, weight guide means on the hub of one of the elements, force-receiving means in said chamber and on the other of said elements, inertia -weights in the chamberand directed'-bysaidguidemeans toapply centrifugal fforee developedtherebycattendant to rotation of 'the -pulley "against the J'force receiving'means in 'an axial direction to force the ila'nge of "such Aother `element 'toward the `iiange of Jthe one element.

i3. Afbelt-driving -pulley comprising c'omplementalfbeltdriving elements each including a hub, a web extending "radially ioutward-irontthe AVhub, lan 4axially Iextendingpilot 'pfose `a Aconical belt=engaging surface `of such flange `col'axially withV the ihub, the hubs 'of `such `elements vandthe least ione ofsuc-h'hubs and rims being 'piloted 'ontheone 'telescopically disposed therewith, Vthe webs 'of such'elements being `s paced apart axially of thehubs 'and rims wherefore the hubs, webs and rims form Lan Vannular weight-receiving chamber, means yiel'dably urgingthe Yelements axially 'apart to increase the'axial spacin'g'between the `belt-engaging. surfaces, pivot means in the chamber on the hub of one ofthe elements, 'inertia 'weights in the'c'ha'mber in axially spaced relationfro'm v` the web of such `one elementandpivo'tally mounted 'on said pvot means to swing radially outward andtoward the web vof the one element'un'der the action of centrifugal force attendant to rotation 'of the pulley, and forcereceiving'means engageable'by said Vweights and carried in .said chamber by the -other element and iextendingbc- K tween the weightsand the webofthe one element to prevent separation of said elements, and `the weights being operable .to apply thecent-rifugal force to said force-.re-

ceiving means vto axially. contract the elements to .diminish the :distance lbetween `the .belt-engaging. surfaces.

L4. The `combination setforth in .c1aim 3, wherein :said :force receiving means is in .the form of pulley assembly maintaining pins mounted in the rim Kof -said .other-element and vprojectingchordally into the chamber-'between 4 the weights-.and the Webof-the one element.

V5. A belt-drivingpulley comprising complemental belt- .driving .elementseach including va hub,;a webextending :radially-outward `from fthehub, an-axially extending pilot trim on :a :radially outwardportion of the web, and a :flange projecting radially outward `:from the Yrim to disposera conical belt-.engaging surface ,of such Vflange coaxially with the hub, the rim of one ,of such .elements lhaving a'radially outer peripheryextending in parallelism -Withthe axis of the hub-of suc-:h.element, `the rimofthe other element havingan :inner .periphery telescopically fpilotedfon-said-outer periphery,the hubs of said elements ';beingwtelescopically disposed, .the websof said elements being spaced apart axially wherefore the webs, hubs-:and

form an .annular weight-receiving chamber,.nreans gyielda'bly .urging lthe-.elements axially apart .to increase the axial spacing between the belt-.engagingsurfaces,

1 fpivotmeansain :theuchamber on :thefhub of .the one element, `,inertia Yweights inthe .eharnberfinnaxiallylspaced .relation-from the web l.of the :one element tandpivotally mounted on said pivot means to swing radially outward radially outward from the hub, an axially extending pilot n rim on a radially outward portion of the web, and 4a flange projecting radially outward from the rim to dispose a conical belt-engaging surface of such flange coaxially with the hub, the hubs ofl such elements and the rims thereof being axially telescopically disposed and at least one of'such hubs and rims being piloted on the one ytelescopically disposed therewith, the webs of such elements being spaced apart-axially of the hubs and rims wherefore the hubs, webs and rims form an annular weight-receiving chamber, the web of one of said elements having bosses axially projecting into said chamber, the web of the other element having notches respectively receivable of said bosses when said elements are axially assembled and to interlock with said bosses to preclude relative rotation of said elements, spring seat recesses respectively lin said bosses, additional spring seat recesses respectively embraced by said notches and respectively coaxial with the boss recesses, and helical compression springs having one end respectively in the boss recesses and their opposite ends respectively in the notch-embraced recesses to yieldably urge the belt-driving elements Irelatively axially apart, and speed respon-v sive means in said chamber operable in response to rotative speed of the pulley to dominate the force of said springs and axially contract said elements to diminish the spacing of the belt-engaging surfaces.

7. The combination set forth in claim 6, wherein certain of the spring seat recesses are of a diameter to rmly hold the ends of the springs inserted thereinto, and wherein the seat recesses coaxial with such certain recesses `are of larger diameter than the'opposite ends of the springs to facilitate the projection of such ends thereinto attendant to axial assembly of the elements.

8. A belt driven pulley comprising a pair of members respectively having conical surfaces which together form a belt receiving groove, said members being relatively movable axially .thereof to vary the width of said groove, a shaft supporting said members, one of said members having abutments thereon comprising cross pins mounted in said one member, said cross pins being located between said weights and a radially extending portion of said other member thereby retaining said members in assembled relation, centrifugal weights mounted on the other of said members for rotation therewith and radially movable on rotation of said members, said weights having plane cam surfaces oblique to a radius and axially engaging said abutments for drawing said members toward each other to reduce the width of said groove as said weights move 4radially in response to rotation of said members. v

9,. A 4belt driven pulley according to claim 8, having spring means interposed between said members and tending to move said members away from each other.

l0. A belt driven pulley according to claim 8, in which each of said members has a web and a ilange, the flanges of said members respectively providing said conical surfaces, and the webs of said members forming a chamber in which said weights are located.

11. A belt driven pulley comprising a pair of members respectively having conical surfaces which together form a belt receiving groove, said members being relatively movable axially thereof to vary .the width of said groove, a shaft supporting said members, one of said members having a pair of notches eccentrically located therein and the other of said members having a pair of bosses engageable in said notches to secure said members together for rotation with each other, one of said members having abutments thereon and the other of said members having centrifugal weights mounted thereon `for rotation therewith and radially movable on rotation of said members, said weights having plane cam surfaces oblique to a radius and axially engaging said'abutments for drawing said members toward each other to reduce the Width of said groove as said weights move radially in response t0 rotation of said members.

12. A belt `driven pulley according to claim 11, in which a pair of springs are mounted in the respective bosses and notches and tend to move said members away from each other.

References Cited in thele of this patent UNITED STATES PATENTS 2,317,339 Steven Apr. 20, 1943 2,496,061 Miner Jan. 31, 1950 2,534,409 Bray Dec. 19, 1950 2,622,446 Shaw Dec. 23, 1952 2,678,566 Oehrli May 18, 1954 FOREIGN PATENTS 18,637 Great Britain of 1909 435,257 Great Britain Sept. 18, 1935 

